Rotational motion- steam engine

The flywheel of a steam engine begins to rotate from rest with a constant angular acceleration of 1.35 rad/s^2. It accelerates for 33.1 s, then maintains a constant angular velocity. Calculate the total angle through which the wheel has turned 47.5 s after it begins rotating.

2. Relevant equations

1. w=wi +alpha(time)

2. theta - theta(initial) = 1/2(w +wi)t

3. The attempt at a solution
I have attempted this problem several times and keep getting the answer wrong!!! (note: I do not know the correct answer for this particular problem)

First I used equation 1 to find the constant angular velocity. Then, since I know that constant velocity means zero acceleration, I used equation 2 to find the total angle. What am I doing wrong? Please help!

The flywheel of a steam engine begins to rotate from rest with a constant angular acceleration of 1.35 rad/s^2. It accelerates for 33.1 s, then maintains a constant angular velocity. Calculate the total angle through which the wheel has turned 47.5 s after it begins rotating.

2. Relevant equations

1. w=wi +alpha(time)

2. theta - theta(initial) = 1/2(w +wi)t

It would help to graph the angular speed as a function of time. The area under the graph is what you are trying to calculate.

If it starts at [itex]\omega = 0[/itex] then [itex]\omega = \alpha t[/itex] and: